1. Field of the Invention
The present invention relates to data transmission and reception in a broadcasting or communication system. More particularly, the present invention relates to an apparatus and method of efficiently recovering data, when data loss occurs on a channel or in a network.
2. Description of the Related Art
In the recent broadcasting and communication environment, data congestion in a network has become serious due to the diversification of multimedia content and the increase of large-size content such as High Definition (HD) content or Ultra High Definition (UHD) content. As a result, content transmitted by a transmitter (e.g. host A) is not received normally at a receiver (e.g. host B) due to loss of a part of the content in a route. Since data is transmitted in packets in many cases, data loss also occurs in packets. As the receiver does not receive a data packet due to data loss over a network, the receiver does not acquire the data of the lost packet. Therefore, various inconveniences may result, including the degradation of audio quality or video quality, display of defective images, omissions of text, and file damage. Accordingly, there exists a need for a technique of recovering data lost during transmission over a network.
One method of supporting recovery in a receiver of data that has been lost during transmission over a network, is to construct a source block with a predetermined number of data packets each having a variable length, called source packets and add repair information such as parity data or repair packets to the source block by Forward Error Correction (FEC) coding. In the presence of lost data, the receiver may decode the data using the repair information.
Each of the source packets to which the repair information is added may not have an intended length and thus may be zero-padded. This means that the conventionally constructed source block may include a large amount of zero padding according to packet lengths. Although zero-padded data is meaningless data not transmitted by the transmitter, the zero-padded data increases the number of symbols in the source block and is involved in generating parity data. Therefore, the zero-padded data causes generation and transmission of parity data for unnecessary information.
The amount of zero padding may be reduced relatively by decreasing an intended length of source packets. However, due to the resulting significant increase in the number of symbols in the source block, a very long FEC code is required. Because an FEC code length available to a system is limited and a longer FEC code increases the complexity of Maximum log-Likelihood (ML) decoding, decoding latency may be lengthened.
Accordingly, there exists a need for a method of constructing a source block more efficiently to reduce the number of code symbols and improve error correction capability by reducing zero-padded data.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.